As it is known, MEMS is the acronym of Micro-Electro-Mechanical Systems and identifies a technology for the integration on a same sustrate, in particular a die of silicon, of glass or of organic material, of devices of various nature, mechanical and/or electronic/electric, integrated in a highly miniaturized form.
In particular, the MEMS technology combines the opto-mechanical properties of micro mechanical devices with the electric properties of integrated electronic circuits.
As it can be easily guessed, some realizations such as, for example, pressure sensors, gas analysers, drug micropumps and dispensers for liquids may require a connection to the MEMS devices, and in particular sensitive elements made therein, with external apparatuses, such as tanks, comprising liquids or gases.
Therefore, one may connect the sensitive element of the MEMS device, which has typical sizes of some microns, with an inlet of the external apparatus, whose sizes may be on the order of millimeters.
To this purpose, the use is known, as shown in FIGS. 1-5, as junction, of a cap-like element 6 with a countershaped body suitably coupled to a package 5 of a MEMS device 3. The cap-like element 6 comprises one or more connection conduits 7 projecting from the body for the connection between the sensitive element of the MEMS device 3 and the external apparatus, this latter being nor shown in these figures.
In particular, the external apparatus may be a micro-tank or, for a microfluidic system, fluidic connection pipes.
The conduits 7 of the cap-like element 6 have such external sizes as to be associated with an inlet of the external apparatus, while they have an internal cavity which is adapted to the sizes of the sensitive element of the MEMS device 3, as shown in particular in FIG. 3.
This solution known for the realization of MEMS systems has some drawbacks.
Generally, the package 5, as shown in FIGS. 4 and 5, comprises the MEMS device 3 which is in turn associated with a suitable substrate 2 of polysilicon or of organic or ceramic material. However, before being associated with the substrate 2, the MEMS device 3 is sandwich-wise interposed between two silicon dies assembled by using a glass-based material and by using a particularly difficult and critical process. The process used also employs a material with a lead oxide content of about 80%.
Moreover, as shown in FIG. 5, the wire micro-junctions among the MEMS device 3 and the electronic circuit 4 associated therewith are made by using gold wires having diameter of some tens of microns, with a process which requires an extreme cleanliness of the surfaces whereon the junction is made and an accurate control of the process parameters.
The cap-like element 6, which defines the junction, may require in turn a rather complicated and critical manufacturing process especially for the realization of the ducts 7, which have extremely small sizes. Moreover, during the assembly, the cap-like element 6 may require an additional step specific for the assembly onto the MEMS system 1 and moreover, due to the particularly small sizes, the ducts 7, projecting from the cap body 6 may be easily deformed.
Thus, the MEMS systems with these junctions may be complex and particularly expensive.